1. Field of Invention
The present invention relates to a hydraulic pressure control system for a torque converter. More particularly, the present invention relates to a hydraulic pressure control system for a torque converter which may increase cooling efficiency by circulating fluid even in operation of a lock up clutch.
2. Description of Related Art
A general torque converter is provided with a lock-up clutch which may transfer torque mechanically.
The lock-up clutch is disposed between a cover (a front cover) which is an input rotary member and a turbine which is an output rotary member.
A space between the front cover and the turbine may be divided into a disengagement side oil chamber and an engagement side oil chamber.
The lock-up clutch is controlled to operate or not according to hydraulic pressure difference between the disengagement side oil chamber and the engagement side oil chamber.
In detail, if a fluid within the disengagement side oil chamber is drained and a fluid is supplied to the engagement side oil chamber, the hydraulic pressure difference between the engagement side oil chamber and the disengagement side oil chamber may allow a friction member of the lock-up clutch is frictionally engaged with to the front cover.
That is, frictional engaging force of the lock-up clutch is increased and then complete frictional engagement of the lock-up clutch is realized. That means lock-up on state of the lock-up clutch is realized.
If a fluid is supplied to the disengagement side oil chamber so that the hydraulic pressure difference between the engagement side oil chamber and the disengagement side oil chamber is reduced, the lock-up clutch is in state of slip.
If the slip of the lock-up clutch is repeated, frictional heat due to the slip is increased, so that durability of the friction members may be deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.